Smith Conrad, Hull M L, Howell S M
Biomedical Engineering Program, One Shields Avenue, University of California, Davis, CA 95616, USA.
J Biomech Eng. 2008 Aug;130(4):044503. doi: 10.1115/1.2907766.
Lengthening of a soft-tissue anterior cruciate ligament (ACL) graft construct over time, which leads to an increase in anterior laxity following ACL reconstruction, can result from relative motions between the graft and fixation devices and between the fixation devices and bone. To determine these relative motions using Roentgen stereophotogrammetry (RSA), it is first necessary to identify the axes of the tibial and femoral tunnels. The purpose of this in vitro study was to determine the error in using markers injected into the portions of a soft-tissue tendon graft enclosed within the tibial and femoral tunnels to define the axes of these tunnels. Markers were injected into the tibia, femur, and graft in six cadaveric legs the knees of which were reconstructed with single-loop tibialis grafts. The axes of the tunnels were defined by marker pairs that were injected into the bones on lines parallel to the walls of the tibial and femoral tunnels (i.e., standard). By using marker pairs injected into the portions of the graft enclosed within the tibial and femoral tunnels and the marker pairs aligned with the tunnel axes, the directions of vectors were determined by using RSA, while a 150 N anterior force was transmitted at the knee. The average and standard deviations of the angle between the two vectors were 5.5+/-3.3 deg. This angle translates into an average error and standard deviation of the error in lengthening quantities (i.e., relative motions along the tunnel axes) at the sites of fixation of (0.6+/-0.8)%. Identifying the axes of the tunnels by using marker pairs in the graft rather than marker pairs in the walls of the tunnels will shorten the surgical procedure by eliminating the specialized tools and time required to insert marker pairs in the tunnel walls and will simplify the data analysis in in vivo studies.
随着时间推移，软组织前交叉韧带（ACL）移植物结构会延长，这会导致ACL重建术后前向松弛度增加，这可能是由于移植物与固定装置之间以及固定装置与骨骼之间的相对运动所致。为了使用X射线立体摄影测量法（RSA）确定这些相对运动，首先必须确定胫骨和股骨隧道的轴线。本体外研究的目的是确定使用注入到软组织肌腱移植物位于胫骨和股骨隧道内部分的标记物来定义这些隧道轴线时的误差。将标记物注入六条尸体腿的胫骨、股骨和移植物中，这些腿的膝关节采用单环胫骨移植物进行重建。隧道轴线由注入骨骼上与胫骨和股骨隧道壁平行的线上的标记物对来定义（即标准方法）。通过使用注入到位于胫骨和股骨隧道内的移植物部分的标记物对以及与隧道轴线对齐的标记物对，在膝关节施加150 N前向力时，使用RSA确定向量方向。两个向量之间角度的平均值和标准差为5.5±3.3度。该角度转化为固定部位延长量（即沿隧道轴线的相对运动）的平均误差和误差标准差为（0.6±0.8）%。通过使用移植物中的标记物对而非隧道壁中的标记物对来确定隧道轴线，将省去在隧道壁中插入标记物对所需的专用工具和时间，从而缩短手术过程，并将简化体内研究中的数据分析。
